The machine tool industry uses machines such as lathes, chucking machines, and the like are available. These machines have a significant variety of spindle sizes and capacity. The spindle sizes available depend to some extent upon the manufacturer of the machines. A number of different standard size spindles are used.
For example, a SC is a rather common size collet—spindle for a number of different machines. Another larger spindle is the American National Standard Institute (ANSI) A2-5 spindle, which may be made to accept the larger 16C collets, but also said spindles may require the use of a smaller SC collets. Thus, the collet adapter of the present invention permits use of the smaller collets on the larger size spindle machines.
The prior art reveals an adapter also intended for adapting a smaller collet to a large spindle. U.S. Pat. No. 4,477,095 disclosers such an adapter which allows the use smaller collets in machines with larger collet seats. These units are available when you do not have the proper size standard collet for the machine but do have the proper size in a smaller style collet. However this prior structure suffers from several disadvantages. Specifically, this unit has many moving parts, and is not to be considered when doing precision work. Because of the number of parts in the assembly, the TIR of the machined diameters to the chucked diameters may be unacceptable. Said adapter includes a tapered head portion engaged with a threaded tubular portion, held in by a faceplate and screws. The tubular portion external threads engage the drawtube, on its exterior surface and threads receives the smaller diameter on its interior surface. Said unit can only be used on specific manufactures machines. It will take 15-30 minutes to change the adaptor.
The prior art reveals an adapter also intended for adapting a smaller collet to a larger spindle. U.S. Pat. No. 2,478,195 disclosers such an adapter that includes a tapered head portion slideably engaged with a threaded tubular portion. The tubular portion in turn threads engages the drawtube of the machine tool on its exterior surface and threads receives the smaller diameter on its interior surface. However this prior structure suffers from several disadvantages. Specifically, upon release of the draw tube for releasing the work, the adapter is just as likely to push out with its head pressure on the work piece, in addition the connection between the head portion and the tubular portion of this adapter is such that significant wear can result between the two pieces which in turn can reduce the accuracy of the machine tool
The primary object of the present invention is to provide an improved collet adapter for adapting a smaller collet of a given size to a larger size machine tool spindle. A further object of the invention is to provide a one-piece collet adapter of improved construction, which can be used in any standard collet chuck or spindle.